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BRUNO GIUSEPPE PIGNATARO

Self-Organization Pathways and Spatial Heterogeneity in Insulin Amyloid Fibril Formation

  • Authors: Foderà, V.; Cataldo, S.; Librizzi, F.; Pignataro, B.; Spiccia, P.; Leone, M.
  • Publication year: 2009
  • Type: Articolo in rivista (Articolo in rivista)
  • OA Link: http://hdl.handle.net/10447/36316

Abstract

At high temperature and low pH, the protein hormone insulin is highly prone to form amyloid fibrils, and for this reason it is widely used as a model system to study fibril formation mechanisms. In this work, we focused on insulin aggregation mechanisms occurring in HCl solutions (pH 1.6) at 60 °C. By means of in situ Thioflavin T (ThT) staining, the kinetics profiles were characterized as a function of the protein concentration, and two concurrent aggregation pathways were pointed out, being concentration dependent. In correspondence to these pathways, different morphologies of self-assembled protein molecules were detected by atomic force microscopy images also evidencing the presence of secondary nucleation processes as a peculiar mechanism for insulin fibrillation. Moreover, combining ThT fluorescence and light scattering, the early stages of the process were analyzed in the low concentration regime, pointing out a pronounced spatial heterogeneity in the formation of the first stable fibrils in solution and the onset of the secondary nucleation pathways.